Louvers of a variety of types of construction have heretofore been used in association with windows for the control of the rays of the sun, for security purposes, and for wind protection. In the past, exterior louvers for the most part have been constructed entirely of metal, glass or wood.
Some of the modern buildings have windows of oblique shapes including trapezoidal shapes. Louver frames constructed in oblique shapes are difficult to aline and have a tendency to become out of alinement or become misalined and this results in considerably more difficulty in maintaining the louvers free to pivot. Another common difficulty encountered with external louvers made of wood or metal is that the wind causes them to slap against one another. Metal louvers do not provide a thermal barrier since they are a good conductor of heat. Wood louvers have a tendency to warp when used in exterior situations.
Shapiro U.S. Pat. No. 3,305,970 discloses a centrally pivoted louver in which the frame members at the ends of the louvers are parallel to one another and which utilizes conventional journal bosses in which the ends of the louvers are mounted. This patent discloses a common lever for simultaneously moving a plurality of louvers.
Stack U.S. Pat. No. 3,151,665 discloses vertical louver doors supported between parallel-spaced tracks, the bottom track having a groove curved in cross section for the reception of a ball bearing. The ball bearing rolls along the groove. The top track has a rectangular groove for the reception of a ball bearing assembly carried by the top panel support.
Tracy et al U.S. Pat. No. 3,113,355 discloses a right angle gear arrangement in a drive train for louvers and utilizes a link common to a plurality of louvers for moving the louvers.